Elevation of serum lipids after chronic administration of amiodarone in rabbits.

Amiodarone hydrochloride is a potent, iodine-containing antiarrhythmic compound with a long elimination half-life, whose cardiac action appears to be mediated through an interference with thyroxine-dependent pathways in the heart. Whether it has any effect on lipid metabolism is not known. Its effect (20 mg/kg per day intraperitoneally) after 3 and 6 weeks of treatment on changes in serum lipoproteins were studied in male New Zealand white rabbits. Serum amiodarone levels reached a steady state (approximately 0.05 microgram/ml) after 3 weeks, and serum reverse T3 (an index of drug dose and duration of treatment) increased 3-4 fold by 3 and 6 weeks. In two discrete sets of studies, serum triglyceride (TG) and total cholesterol (CHOL) increased significantly (P less than 0.01) after 3 and 6 weeks on amiodarone when compared to the values in a control series of animals. Phospholipid (PL) levels were not changed. Very low density lipoproteins (VLDL) in the drug-treated groups showed a significant increase in triglyceride (P less than 0.01) and in apoprotein B (P less than 0.05). There was no change in low density lipoprotein-apoprotein B levels. Whether the abnormalities observed in serum lipids induced by amiodarone are mediated through changes in thyroid hormones or occur as a result of a direct effect on lipid metabolism is unknown, but the problem merits further investigation.